/*----------------------------------------------------------------------------*/
/* Copyright (c) FIRST 2008-2016. All Rights Reserved.                        */
/* Open Source Software - may be modified and shared by FRC teams. The code   */
/* must be accompanied by the FIRST BSD license file in the root directory of */
/* the project.                                                               */
/*----------------------------------------------------------------------------*/

#include "HAL/cpp/Resource.h"
#include <cstddef>
#include "HAL/Errors.h"
#include "HAL/cpp/priority_mutex.h"

namespace hal {

priority_recursive_mutex Resource::m_createLock;

/**
 * Allocate storage for a new instance of Resource.
 * Allocate a bool array of values that will get initialized to indicate that no
 * resources have been allocated yet. The indicies of the resources are [0 ..
 * elements - 1].
 */
Resource::Resource(uint32_t elements) {
  std::lock_guard<priority_recursive_mutex> sync(m_createLock);
  m_isAllocated = std::vector<bool>(elements, false);
}

/**
 * Factory method to create a Resource allocation-tracker *if* needed.
 *
 * @param r -- address of the caller's Resource pointer. If *r == NULL, this
 *    will construct a Resource and make *r point to it. If *r != NULL, i.e.
 *    the caller already has a Resource instance, this won't do anything.
 * @param elements -- the number of elements for this Resource allocator to
 *    track, that is, it will allocate resource numbers in the range
 *    [0 .. elements - 1].
 */
/*static*/ void Resource::CreateResourceObject(Resource** r,
                                               uint32_t elements) {
  std::lock_guard<priority_recursive_mutex> sync(m_createLock);
  if (*r == NULL) {
    *r = new Resource(elements);
  }
}

/**
 * Allocate a resource.
 * When a resource is requested, mark it allocated. In this case, a free
 * resource value
 * within the range is located and returned after it is marked allocated.
 */
uint32_t Resource::Allocate(const char* resourceDesc) {
  std::lock_guard<priority_recursive_mutex> sync(m_allocateLock);
  for (uint32_t i = 0; i < m_isAllocated.size(); i++) {
    if (!m_isAllocated[i]) {
      m_isAllocated[i] = true;
      return i;
    }
  }
  // TODO: wpi_setWPIErrorWithContext(NoAvailableResources, resourceDesc);
  return ~0ul;
}

/**
 * Allocate a specific resource value.
 * The user requests a specific resource value, i.e. channel number and it is
 * verified unallocated, then returned.
 */
uint32_t Resource::Allocate(uint32_t index, const char* resourceDesc) {
  std::lock_guard<priority_recursive_mutex> sync(m_allocateLock);
  if (index >= m_isAllocated.size()) {
    // TODO: wpi_setWPIErrorWithContext(ChannelIndexOutOfRange, resourceDesc);
    return ~0ul;
  }
  if (m_isAllocated[index]) {
    // TODO: wpi_setWPIErrorWithContext(ResourceAlreadyAllocated, resourceDesc);
    return ~0ul;
  }
  m_isAllocated[index] = true;
  return index;
}

/**
 * Free an allocated resource.
 * After a resource is no longer needed, for example a destructor is called for
 * a channel assignment class, Free will release the resource value so it can
 * be reused somewhere else in the program.
 */
void Resource::Free(uint32_t index) {
  std::lock_guard<priority_recursive_mutex> sync(m_allocateLock);
  if (index == ~0ul) return;
  if (index >= m_isAllocated.size()) {
    // TODO: wpi_setWPIError(NotAllocated);
    return;
  }
  if (!m_isAllocated[index]) {
    // TODO: wpi_setWPIError(NotAllocated);
    return;
  }
  m_isAllocated[index] = false;
}

}  // namespace hal